1. Field of the Invention
The present invention relates generally to aircraft instrumentation displays and more particularly to a vertical deviation indication and prediction system for providing situational awareness of the present vertical flight path and an efficient indication of a manner for intercepting the desired flight path.
2. Description of the Related Art
The depiction of lateral navigation (LNAV) information in the flight deck has matured significantly over recent years. It is fairly easy for pilots to visualize their position on the active (FMS) flight plan, understand where the next waypoint occurs, the direction of the next leg, and visualize any offsets when deviating. Furthermore, when navigating by heading/track, it is also a straightforward matter to manually create an intercept path to rejoin the flight plan.
The same cannot be said for Vertical Navigation (VNAV). One of the principal reasons that pilots become confused when using VNAV is that they do not have a comprehensive visualization tool for the vertical flight plan. Recent designs by air transport aircraft manufacturers have implemented vertical situation displays. However, many smaller/older aircraft do not possess anything more than simple vertical deviation indicators that show the current deviation from the vertical flight plan. No information is provided about the next vertical flight plan segment beyond the next flight plan waypoint.
An example, of a Vertical Situation Display (VSD) for use with Boeing aircraft is described in the article entitled, “Vertical Situation Display for Improved Flight Safety and Reduced Operating Costs”, Aero, No. 20, October 2002, pages 3–11. The Boeing VSD works in conjunction with the terrain-mapping feature of the terrain awareness and warning system (TAWS), a Honeywell enhanced ground proximity warning system. It provides an intuitive presentation of the vertical situation relative to the surrounding terrain and the final approach decent path. In addition to terrain alerting, the TAWS provides a lateral, or top-down, view of terrain. The VSD depicts a profile, or side view, of terrain and flight path data.
U.S. Pat. No. 6,720,891, issued to Chen et al., entitled, “Vertical Situation Display Terrain/Waypoint Swath, Range to Target Speed, and Blended Airplane Reference” discloses a flight information display for the flight deck of an aircraft showing a pictorial side view of the flight path or the area directly in front of the aircraft area having a selected distance of at least 0.5 nautical miles, comprising (a) a pictorial representation to scale of the profile of the highest elevations of a swath of terrain along said path or area, (b) an icon positioned on the left or right side of the display representing the aircraft, the altitude of which is to scale with the height of the terrain, and (c) an altitude reference scale; wherein the width of the swath is at least 0.1 nautical miles and no greater than the distance of the minimum accuracy of the means for determining the aircraft's location.
U.S. Pat. No. 5,936,552, issued to Wichgers et al., entitled, “Integrated Horizontal and Profile Terrain Display Format For Situational Awareness”, discloses a visual display format for a terrain situational awareness system comprising a horizontal terrain elevation view and a profile terrain elevation view of potential terrain hazards integrated onto a single display.
U.S. Pat. No. 6,154,151, issued to Wichgers et al., entitled, “Integrated Vertical Situation Display for Aircraft”, discloses an integrated vertical situation display (IVSD) for an aircraft, and method of displaying vertical situation information. The IVSD includes an electronic display for displaying the vertical situation of the aircraft, input interfaces for receiving vertical profile information signals, and a processing circuit for reading the information signals and generating display signals applied to the display therefrom. The display has a vertical profile view area to display the vertical situation in front of, above, and below the aircraft. The information sources may include a flight management system, traffic alert and collision avoidance system (TCAS) and a ground proximity warning system. Vertical situations are displayed by visual indicia representing, for example, aircraft position, path angle, flight path, waypoints, TCAS targets, altitude preselect, decision height, runway, ground contour, and vertical speed. The integrated display minimizes the cognitive workload of the operator in assessing the total vertical situation.
U.S. Pat. No. 6,154,151, issued to Barber et al., entitled, “Enhanced Vertical Terrain Profile Display”, discloses a flight display for use in an avionics system that has a visual display format to show an enhanced vertical situation of an aircraft. Included is a vertical terrain profile display that displays terrain in front of the aircraft over a selected range and a selected swathe width. The vertical terrain profile display shows a side-on terrain profile view with a digital display of the selected swathe width and a display of range in front of the aircraft. A plan view of the aircraft position is included that shows swathe lines on either side of an aircraft to show the selected swathe width. A means for selecting the swathe width by the pilot is provided. The vertical terrain profile display may be changed into a end-on vertical terrain profile view over the selected swathe width. The end-on terrain profile view has a digital display of the selected range and a digital display of the selected swathe width on each side of the aircraft.
As will be disclosed below, the present invention affords a simple method and symbology for providing the pilot with much improved situational awareness, regarding the position of the airplane relative to the current vertical flight plan segment, and the position relative to an extension (rearwards extrapolation) of the next vertical flight plan segment.